Protective eyewear is highly useful in many industrial, sports and leisure activities, and in numerous of these activities use of protective eyewear is mandatory under industrial and/or governmental regulations. A partial listing of situations where use of protective eyewear is now common includes, but is not limited to, environments where there is dust, pollution and sparks, flying fragments of various sizes, high wind, and in chemical laboratories, welding, machining and assembly areas, and essentially in any environment where any foreign substance or particle could move into contact with the eye. Exemplary areas of protective eyewear use in sports and leisure fields, include skiing, bicycling, flying, vehicle racing of all types, water sports, skydiving and hobbies. Still further areas of use include use in respirator masks and in gas masks.
The focus of the present invention is on protective eyewear which includes prescription lenses. As used herein, protective eyewear or safety eyewear includes eye shields of single or dual lens styles, face masks, goggles, safety spectacles, safety eyeglasses and safety eyewear generally. For convenience herein, the terms “protective eyewear” or “safety eyewear” will be used to cover all the protective eyewear articles described above.
Safety eyewear products in the form of eye shields, goggles, facemasks and helmets with eye shields are well known and are effective for their protective purposes. However, use of these products by persons who wear prescription eyeglasses, often leads to problems. Most safety eyewear does not fit well or does not fit at all over basic eyeglasses. Where it might fit well, it would be excessively large. To circumvent this problem, some safety eyewear is designed to include lens mounting components to hold individual prescription lenses within the safety eyewear frame. While the concept of mounting prescription lenses in an eye shield is basically simple, there have been difficulties and inadequacies with the results.
A principal problem has been lack of adjustability, namely the inability to achieve the same full adjustability of lenses in a safety shield that an optician could achieve with a basic eyeglass frame.
A basic eyeglass frame is adjustable about a variety of axes and planes, such as:                a. to tilt each lens about a horizontal axis,        b. to tilt each lens about a vertical axis,        c. to move each lens up, down, forward or backward,        d. to angulate each lens relative to the frame or relative to the other lens, and        e. to twist a lens about selected axes.        
These adjustments are possible with many eyeglass frames, because of the traditional and basic eyeglass construction, a fundamental example being a frame comprising a pair of eye wires joined by a central bridge, and a pair of earpieces, or temples, extending from the frame. The shapes, sizes and styles of frames and central bridges vary greatly.
For reasons of comfort, safety and aesthetics, it is often desirable to form a safety shield as a concave curve for positioning adjacent the front of the face. Normal prescription eyeglass frames have the set of lenses side-by-side in a generally flat or only mildly curved arc. In eye shields of contemporary design and style, the shield curvature is typically greater than the curvature that occurs in an eyeglass frame, and consequently, lenses mounted on the interior surface at the shield curvature can create optical distortion for the wearer.
In summary, the current safety eyewear has problems and disadvantages pertaining to the inability to fully adjust prescription lenses after they are inserted in the mounting frame, and the cost and difficulty to replace prescription lenses in safety eyewear.